This is a very, very introductory book with nearly zero mathematical rigour but still excellent to build up your core concepts. The book progresses very slow, explaining each and every bit clearly. There's a lot of visual help to supplement each step of a data structure, algorithm.

The book uses Ruby, Python and Javascript code snippets to explain which I was a bit frustating for I always like my algorithms books language agnostic. It isn't a big problem if you know a programming language like C/C++ or Java but still you need to look up certain syntax - which severs your focus.